I found a plunger, it is 1.61" long, 1.08" diameter. I don't know if it will work for your starter since it came out of a direct drive starter that would not work on my hemi because it had the wrong nose. The part number for the hemi plunger is 1889151.

I also found a cross reference for this number on a website for AMSCO Valley Forge, who sells starter parts. Their part number is W5236. There was no price listed and they want you log-in and register but there is a note that says "do not contact us unless you are a business in the automotive electrical industry".

If you want the one I have, PM me with your address and I will send it you, or you can pick it up near Hagerstown, MD.

Jim